A paper has been submitted on new methods for analyzing case- control studies in which controls were selected by cluster sampling. A conference was held on the effects of measurement errors on the reliability of epidemiologic studies, and staff are editing papers from this conference for publication. Methods for projecting cancer risk for individuals and populations were applied to cohorts at high risk for breast cancer and to those exposed to radiation, variance calculations for such risk projections were derived for cohort data and for attributable risk estimates obtained from logistic models for case-control data. Complex models of the effects of joint exposures were used to study the risks associated with radon exposure. A paper appeared on indirect corrections for confounding in occupational cohort data in which confounder information is not available for individuals. A paper appeared that describes the calculation of standardized mortality ratios and their variances from case-cohort data and methods for assessing the efficiency of the case-cohort design for internal comparisons have been submitted for publication. Sample size calculations were published for case-control designs using logistic regression models with continuous covariates and general relative risk functions. Papers appeared on the effects of pooling data across strata in perfectly balance cohort and case-control designs and on robust methods of covariate adjustment for testing for treatment effects in randomized clinical trials. Software is being developed to carry out epidemiologic analyses on the personal computer. A manuscript is in press that describes the method of "back calculation" for projecting the size of the acquired immune deficiency syndrome (AIDS) epidemic, and two papers appeared that describe biases in the conventional analysis of prevalent cohort data, such as seropositive persons at risk for AIDS. A compartmental model has been developed to evaluate the effects of potential interventions, like screening for human immunodeficiency virus, on the spread of the epidemic.